Prenatal exposure to cocaine has been demonstrated to produce neurobehavioral changes in humans and laboratory animals. In contradiction are findings that suggest the effects are minimal and transient. At the base of this discrepancy are issues such as CNS exposure during critical periods of development, the age of subject assessment, and the selection of valid neurobehavioral measures. The acoustic startle response (ASR) is widely regarded as a measure of CNS function. Since sensory and motor components of ASR are sensitive to the effects of toxicants, and because response performance is affected by aging, ASR was selected as a functional index of the longitudinal effects of prenatal cocaine. An objective and fine-grained ASR analysis is regarded as capable of differentiating behavioral changes due to normal aging from long-term changes related to prenatal drug exposures. Age * Treatment interactions are anticipated for cocaine-exposed rats. Groups of pregnant rats will be orally administered 25 or 50 mg/kg cocaine daily from gestation days 6 to 20. ASR will be examined in 2, 8, 14, & 20 month-old offspring groups. Subject responses will be converted to an electrical signal, digitized, and processed via computer. In addition to traditional measures, a comprehensive whole wave analysis will be performed. Techniques to isolate subject and system components are use.